Field of the Invention
The present invention relates to a liquid supply system which supplies liquid through use of a pump.
Description of the Related Art
Conventionally, there has been known a chemical supply system in which a working chamber and a pump chamber of a pump are separated from each other by a diaphragm, and air serving as a working fluid is supplied to and discharged from the working chamber so as to change the volume of the pump chamber, to thereby discharge and suck a chemical solution (see Japanese Patent No. 5342489). In the chemical supply system disclosed in the patent, when charging of the chemical solution into the pump chamber is started, the hydraulic head pressure of the chemical solution is estimated. Specifically, in a state in which the working chamber is closed so as to serve as a closed space, an open-close valve in a suction-side passage communicating with the pump chamber and an open-close valve in a discharge-side passage communicating with the pump chamber are brought into the closed state, and the open-close valve in the suction-side passage is then brought into the open state. Subsequently, the pressure within the working chamber which increases as a result of flow of the chemical solution into the pump chamber is detected, and the maximum value of the detected pressure is used as the estimated hydraulic head pressure.
However, in the case of the chemical supply system disclosed in the patent, it is necessary to wait until the pressure within the working chamber reaches the maximum value, and estimation of the hydraulic head pressure cannot be performed quickly.